1. Field of the Invention
The present invention relates to a magnetic recording and playback method and apparatus for recording a digital signal onto magnetic tape and playing back a digital signal therefrom.
2. Description of the Related Art
Recently, portable camera-integrated digital video tape recorders, and desktop digital video tape recorders which record digital video signals and digital audio signals have appeared.
As a recording method for the digital video tape recorder, there is a format which is commonly called the xe2x80x9cDV methodxe2x80x9d (IEC (International Electrotechnical Commission) 61834 helical scan digital video tape cassette recording system using 6.35 mm magnetic tape for consumer use: 525/60, 625/50, 1125/60, and 1250/50 systems). In this DV method, the width of the video tape used is 6.35 mm (=xc2xc inch), which is narrower than the tape width of video tape used in other recording methods, for example, the 8 mm method (IEC 60843 helical scan video tape cassette recording system using 8 mm magnetic tape for consumer use) for conventional analog video tape recorders.
Also, in the DV method, in spite of the fact that the tape width is narrower than that of a conventional tape, signals to be recorded are compressed and the recording density is increased, thereby allowing for higher image quality and for a longer recording time than that in the recording method in conventional analog video tape recorders.
FIG. 4 shows the track structure in the DV method, in which there is provided in sequence from the start of the track, an ITI (Insert and Track Information) sector (ITI), which serves as a time-axis reference during so-called xe2x80x9cafter-recordingxe2x80x9d, and an audio sector (Audio) via an inter-track gap (ITG) Gap1, and a video sector (Video) via another inter-track gap Gap2, and after that, a subcode sector (Subcode) is provided via another inter-track gap Gap3.
The reason the sections between the sectors are separated by Gap1, Gap2, Gap3, etc., in this manner is to absorb the wobbling of the position of each area due to rotational variation in the head drum, the expansion and shrinkage of tape due to environmental storage conditions, curving of tracks in the direction of the width of the tape, during the so-called xe2x80x9cafter-recordingxe2x80x9d in which audio data, etc., is additionally recorded over data which has already been recorded.
However, in the DV method, the ratio of all the inter-track gaps (Gap1, Gap2, and Gap3: a total of 2875 bits) occupied in the effective tracks (134850 bits) is 2% (2875/134850, which is approximately equal to 0.02).
The inter-track gaps Gap1, Gap2, and Gap3 are provided to prevent interference between the sections of an insert-and-track-information sector (ITI), an audio sector (Audio), a video sector (Video), and a subcode sector (Subcode), and are not portions used for actually recording data.
Therefore, if the ratio of the inter-track gaps Gap1, Gap2, and Gap3) occupied in an effective track is decreased so that the tracks are effectively used as portions where data is actually recorded, the efficiency at which the tape can be used is improved.
In view of the above, an object of the present invention is to minimize the ratio of the inter-track gaps occupied in each track of a magnetic tape so that the amount of effective data which can be recorded on one track is increased.
To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a magnetic recording and playback method for recording digital data on a magnetic tape by a helical scan method and for playing back digital data recorded on a magnetic tape by a helical scan method, the magnetic recording and playback method comprising the steps of: providing in sequence on each track on a magnetic tape a first recording area containing at least an audio sector, and a second recording area containing at least an insert-and-track-information sector, one of a video sector and an audio-video-mixed sector, and a subcode sector, an inter-track gap provided between the recording areas; and recording data continuously on each sector of the first and second recording areas, wherein the data in the first recording area can be rewritten after recording onto the magnetic tape is terminated.
Therefore, since data is written continuously into each sector of the first and second recording areas, wasted portions of each track, which would otherwise not be used for recording data, are reduced, making it possible to improve the efficiency at which a magnetic tape is used.
According to another aspect of the present invention, there is provided a magnetic recording and playback apparatus for recording digital data on a magnetic tape by a helical scan method and for playing back digital data recorded on a magnetic tape by a helical scan method, the magnetic recording and playback apparatus comprising: a unit for providing in sequence on each track on a magnetic tape a first recording area containing at least an audio sector, and a second recording area containing at least an insert-and-track-information sector, one of a video sector and an audio-video-mixed sector, and a subcode sector, an inter-track gap provided between the recording areas; and a recording unit for recording data continuously on each sector of the first and second recording areas, wherein only the data in the first recording area can be rewritten by the recording unit after recording onto the magnetic tape is terminated.
Therefore, since data is written continuously into each sector of the first and second recording areas, wasted portions of each track, which would not be used for recording data, are reduced, making it possible to improve the efficiency at which a magnetic tape is used.